13,117 research outputs found

    Tang, Eric

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    ROSENTHAL, Eric Inventory of documents

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    COVERAGE 1904; 1 File; 011 metre.Private papers of Eric Rosenthal, author, journalist and broadcaster

    Width-parameterized SAT: time-space tradeoffs,

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    Alekhnovich and Razborov (2002) presented an algorithm that solves SAT on instances ϕ of size n and tree-width TW(ϕ), using time and space bounded by 2O(TW(ϕ))nO(1). Although several follow-up works appeared over the last decade, the first open question of Alekhnovich and Razborov remained essentially unresolved: Can one check satisfiability of formulas with small tree-width in polynomial space and time as above? We essentially resolve this question, by (1) giving a polynomial space algorithm with a slightly worse run-time, (2) providing a complexity-theoretic characterization of bounded tree-width SAT, which strongly suggests that no polynomial-space algorithm can run significantly faster, and (3) presenting a spectrum of algorithms trading off time for space, between our PSPACE algorithm and the fastest known algorithm. First, we give a simple algorithm that runs in polynomial space and achieves run-time 3TW(ϕ)lognnO(1), which approaches the run-time of Alekhnovich and Razborov (2002), but has an additional log n factor in the exponent. Then, we conjecture that this annoying log n factor is in general unavoidable. Our negative results show our conjecture true if one believes a well-known complexity assumption, which is the SC ≠ NC conjecture and its scaled variants. Technically, we base our result on the following lemma. For arbitrary k, SAT of tree-width logkn is complete for the class of problems computed by circuits of logarithmic depth, semi-unbounded fan-in and size 2O(logkn) (SAC1 when k=1). Problems in this class can be solved simultaneously in time-space (2O(logk+1n),O(logk+1n)), and also in (2O(logkn), 2O(logkn)). Then, we show that our conjecture (for SAT instances with poly-log tree-width) is equivalent to the question of whether the small-space simulation of semi-unbounded circuit classes can be sped up without incurring a large space penalty. This is a recasting of the conjecture that SAC1 (and even its subclass NL) is not contained in SC. Although we cannot hope for an improvement asymptotically in the exponent of time and space, we introduce a new algorithmic technique which trades constants in the exponents: for each ε with 0<ε<1, we give an algorithm in time-space (31.441(1−ε)TW(ϕ)log|ϕ||ϕ|O(1),22εTW(ϕ)|ϕ|O(1)). We systematically study the limitations of our technique for trading off time and space, and we show that our bounds are the best achievable using this technique.Licensed under a Creative Commons Attribution License (CC-BY) http://creativecommons.org/licenses/by/3.0/Peer reviewe

    tritrophic-dispersal-model: Code used for creating figures for "Non-hierarchical dispersal promotes stability and resilience in a tri-trophic metacommunity"

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    &lt;p&gt;This is the commented code used for creating figures for the paper. Any questions regarding the code should be directed to the corresponding author and repository owner (Eric Pedersen). &lt;/p&gt

    Eric Velazquez Spanish Language Picture Book Award 2022 Acceptance Speech

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    Author Eric Velazquez gives his Silver Medal acceptance speech for Pulpo Guisado (Holiday House)https://educate.bankstreet.edu/spanishlanguageaward/1001/thumbnail.jp

    Eric C. Lincoln, Professor of Sociology and Religion, 1971

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    This is an interview with Eric C. Lincoln. Eric was a Professor of Sociology and religion, Union Theological Seminary and author of many books and articles on Negro history. In this recording the contributors discuss local memphis politics, sociology, and race relations compared to that of other cities in the South and the rest of the country

    Interview with Eric Bentley, author, drama critic, and playwright

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    Distinguished drama critic and Bertolt Brecht scholar, Eric Bentley is interviewed by WTMJ-TV host Jim Peck and John B. Fuegi, associate professor of Comparative Literature. Bentley recalls his association with Brecht, the critical and creative aspects of literature, and his interest in writing plays for the theater.GrayscaleSoun

    Review of \u3cem\u3eUnsettled: Cambodian Refugees in the New York City Hyperghetto\u3c/em\u3e. Eric Tang. Reviewed by Robert Forrant

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    Eric Tang, Unsettled: Cambodian Refugees in the New York City Hyperghetto. Temple University Press, (2015), 220 pages, 24.95(paperback);24.95 (paperback); 70 (hardcover)
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